A study that sought to understand if the California nurse-to-patient ratio law improves nurse safety showed promising results, according to the article, “California’s Nurse-to-Patient Ratio Law and Occupational Injury,” published May 2015 in the International Archives of Occupational and Environmental Health.
California is the only state to govern a minimum nurse-to-patient ratio law for various units. In general, the ratio is one nurse to five patients. The law has been in place since 2004.
Researchers asked: “Could the law improve safety for the nurses themselves?” To find the answer, they looked at data from the U.S. Bureau of Labor Statistics’ Survey of Occupational Injuries and Illnesses. The SOII collects data from 150,000 to more than 200,000 private firms, depending on year.
Authors of the study chose injury and illness data from 1999 to 2009 and combined that with data on employment in hospitals in California and the rest of the U.S. from SOII and the California Employment Development Department, using a “difference-in-differences” process.
“The ‘difference-in-differences’ method attempts to mimic a randomized trial, based on the assumption that a policy change is enacted independent of the underlying temporal trend in that population’s outcomes,” researchers wrote. “This method helped us account for a nationwide downward trend in workplace injuries and separate the effects of California’s staffing mandates attributable to the new law.”
They compared differences in years 2001 to 2003 with 2005 to 2007 in both California and the other 49 states combined. Their results showed the most probable difference-in-differences estimate indicated California law was associated with 55.57 fewer occupational injuries and illnesses per 10,000 RNs per year, a value 32% lower than the expected rate without the law, based on injury and illness rates before the law was enacted.
“The corresponding estimated reduction in injury and illness rates for licensed practical nurses was 38%,” they wrote.
Researchers speculate that improved staffing ratios could lower rates of injuries and illnesses to nurses in many ways, such as preventing back and shoulder injuries if more nurses were staffed to help move patients. There could be fewer needle-stick injuries if nurses collected blood in a less time-pressured manner.
Some of the minimum nurse-to-patient ratios in the state of California are: critical care unit, 1:2; ICU newborns, 1:2; labor and delivery, 1:2 for active labor patients and 1:4 for antepartum and postpartum; pediatric service unit, 1:4; and ED, 1:4.
Researchers concluded further research is needed to see if reductions are maintained over time.
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